Cold Water Diving November 10, 2010 by lukesheppard

As winter starts to set in and the temperature drops there is more that we need to bear in mind before each dive. I certainly don’t want to put anyone off but diving in cold water creates a new set of challenges that need to be prepared for before actually going diving. Every piece of equipment that you use needs to be considered, checked and corrected/upgraded if it isn’t up to scratch. As always your kit is life support equipment, if it fails or isn’t up to the job you put your life in danger every time you get in the water. This is no more true than when we, as divers, encounter extreme conditions. If you think about it, its not just the obvious kit either like your regulators and thermal protection. What about the battery status of your dive computer? The cold can seriously affect the chemical reactions within the battery, reducing the performance of the battery in cold conditions. When you check it prior to the dive the battery will probably be nice and warm after you’ve travelled to your dive location but once you’ve jumped in and shocked it with the temperature change its not uncommon for the dive computer to report a low battery status and possibly even shut down as a result of insufficient current. All these little things can massively affect the outcome out your dive, if you even get in. So what are some of the main things to remember? Regulators

• Your regulators should be cold water certified when diving in water temperatures below 10 degrees Celsius
• Avoid excessive testing on the surface, especially using the purge button as this causes significant temperature drop in the first and second stages which can allow any moisture to freeze.
• Avoid breathing from or exhaling through your regulators whilst on the surface to prevent exhaled moisture freezing on the second stage components.
• Reduce the load on your first stage by avoiding excessive breathing and inflating your BCD / wing / drysuit whilst inhaling.

Thermal Protection Proper thermal protection is essential with a drysuit and appropriate thermal layers being an must, especially if you want to be in the water for any length of time. The best way to protect yourself is to layer up, ideally at least three. Three layers provides a base layer which is usually a fast wicking material to draw moisture away from the skin, then your primary insulation layer with your outer layer as the drysuit. Obviously the suit you wear will affect the other two layers as a neoprene drysuit will provide better thermal protection than a membrane suit. There are alternatives that break this mould such as the Waterproof D1 Hybrid drysuit which uses a non-compressible layer to maintain the air space around your body and also the Fourth Element Halo 3D undersuit which uses similar technology in key areas. It also goes without saying that you need to protect your extremities as well. Your hands and feet can quickly get cold which in turn starts to lower your core temperature as the cold blood returns to your heart. The body tries to counter this by restricting the flow to these cold areas to maintain core temperature but its definitely good practice to wear high quality, well fitting and thick gloves in cold water. Don’t forget your head as well, up to a third of your body heat can be lost through your head so make sure its well protected with a good thick hood. The Little Things As mentioned before the cold can affect your dive computer, reducing the performance of the battery and possibly shutting it down. The same goes for any other battery operated devices like your torch, make sure you carry a small spare in case your main fails. Try to avoid leaving your cylinder laying on the cold floor and prevent even the smallest drop of water getting into the regulators when fitting them. With all the extra layers on you’re likely to need extra weight, make sure you perform a buoyancy check before you set off on your dive. Being light towards the end of the dive is dangerous. Thick gloves make donning and doffing fins harder, similarly pressing and releasing clips is the same. Make sure you are able to operate all of your releases comfortable and safely without the need to remove your gloves. If you can’t handle a vital clip underwater because of your 5mm or thicker gloves things could get a bit sticky. Generally be prepared for the cold. If you lose or need to replace your mask for whatever reason it can be a real shock to the system to have that cold water on the face and can cause divers to lock up, struggle to breathe or even panic. If you’re diving in a fresh water lake and the temperature is low enough for ice to form on the surface be sure to reel off from your entry point so that you always now where a safe exit point is. At the end of the day the idea is to be safe, plan your dive and stick to it. If you do that and bear in mind the conditions it should lead to a very enjoyable (though chilly) dive.